public static ScrollMetrics copyWith(ScrollMetrics it,
double?minScrollExtent = null,
double?maxScrollExtent = null,
double?pixels = null,
double?viewportDimension = null,
AxisDirection?axisDirection = null,
double?viewportFraction = null
)
{
if (it is IPageMetrics)
{
return(new PageMetrics(
minScrollExtent: minScrollExtent ?? it.minScrollExtent,
maxScrollExtent: maxScrollExtent ?? it.maxScrollExtent,
pixels: pixels ?? it.pixels,
viewportDimension: viewportDimension ?? it.viewportDimension,
axisDirection: axisDirection ?? it.axisDirection,
viewportFraction: viewportFraction ?? ((IPageMetrics)it).viewportFraction
));
}
return(new FixedScrollMetrics(
minScrollExtent: minScrollExtent ?? it.minScrollExtent,
maxScrollExtent: maxScrollExtent ?? it.maxScrollExtent,
pixels: pixels ?? it.pixels,
viewportDimension: viewportDimension ?? it.viewportDimension,
axisDirection: axisDirection ?? it.axisDirection
));
}
bool _handleScrollNotification(ScrollNotification notification)
{
ScrollMetrics metrics = notification.metrics;
if (metrics.maxScrollExtent <= metrics.minScrollExtent)
{
return(false);
}
if (notification is ScrollUpdateNotification ||
notification is OverscrollNotification)
{
if (_fadeoutAnimationController.status != AnimationStatus.forward)
{
_fadeoutAnimationController.forward();
}
_fadeoutTimer?.cancel();
_painter.update(notification.metrics, notification.metrics.axisDirection);
}
else if (notification is ScrollEndNotification)
{
if (_dragScrollbarPositionY == null)
{
_startFadeoutTimer();
}
}
return(false);
}
public override float applyBoundaryConditions(ScrollMetrics position, float value)
{
if (!this.enableOverScroll)
{
if (value < position.pixels &&
position.pixels <= position.minScrollExtent)
{
return(value - position.pixels);
}
if (value < position.minScrollExtent &&
position.minScrollExtent < position.pixels)
{
return(value - position.minScrollExtent);
}
if (position.maxScrollExtent <= position.pixels &&
position.pixels < value)
{
return(value - position.pixels);
}
if (position.pixels < position.maxScrollExtent &&
position.maxScrollExtent < value)
{
return(value - position.maxScrollExtent);
}
}
return(0.0f);
}
public static float extentInside(this ScrollMetrics it)
{
D.assert(it.minScrollExtent <= it.maxScrollExtent);
return(it.viewportDimension
- (it.minScrollExtent - it.pixels).clamp(0, max: it.viewportDimension)
- (it.pixels - it.maxScrollExtent).clamp(0, max: it.viewportDimension));
}
bool _handleScrollNotification(ScrollNotification notification)
{
ScrollMetrics metrics = notification.metrics;
if (metrics.maxScrollExtent <= metrics.minScrollExtent)
{
return(false);
}
if (!_useCupertinoScrollbar.Value &&
(notification is ScrollUpdateNotification ||
notification is OverscrollNotification))
{
if (_fadeoutAnimationController.status != AnimationStatus.forward)
{
_fadeoutAnimationController.forward();
}
_materialPainter.update(
notification.metrics,
notification.metrics.axisDirection
);
if (!widget.isAlwaysShown)
{
_fadeoutTimer?.cancel();
_fadeoutTimer = Timer.create(ScrollbarUtils._kScrollbarTimeToFade, () => {
_fadeoutAnimationController.reverse();
_fadeoutTimer = null;
});
}
}
return(false);
}
public override Simulation createBallisticSimulation(ScrollMetrics position, float velocity)
{
D.assert(
position is _FixedExtentScrollPosition,
() => "FixedExtentScrollPhysics can only be used with Scrollables that uses " +
"the FixedExtentScrollController"
);
_FixedExtentScrollPosition metrics = (_FixedExtentScrollPosition)position;
if ((velocity <= 0.0f && metrics.pixels <= metrics.minScrollExtent) ||
(velocity >= 0.0f && metrics.pixels >= metrics.maxScrollExtent))
{
return(base.createBallisticSimulation(metrics, velocity));
}
Simulation testFrictionSimulation =
base.createBallisticSimulation(metrics, velocity);
if (testFrictionSimulation != null &&
(testFrictionSimulation.x(float.PositiveInfinity) == metrics.minScrollExtent ||
testFrictionSimulation.x(float.PositiveInfinity) == metrics.maxScrollExtent))
{
return(base.createBallisticSimulation(metrics, velocity));
}
int settlingItemIndex = ListWheelScrollViewUtils._getItemFromOffset(
offset: testFrictionSimulation?.x(float.PositiveInfinity) ?? metrics.pixels,
itemExtent: metrics.itemExtent,
minScrollExtent: metrics.minScrollExtent,
maxScrollExtent: metrics.maxScrollExtent
);
float settlingPixels = settlingItemIndex * metrics.itemExtent;
if (velocity.abs() < tolerance.velocity &&
(settlingPixels - metrics.pixels).abs() < tolerance.distance)
{
return(null);
}
if (settlingItemIndex == metrics.itemIndex)
{
return(new SpringSimulation(
spring,
metrics.pixels,
settlingPixels,
velocity,
tolerance: tolerance
));
}
return(FrictionSimulation.through(
metrics.pixels,
settlingPixels,
velocity,
tolerance.velocity * velocity.sign()
));
}
public ScrollStartNotification(
ScrollMetrics metrics = null,
BuildContext context = null,
DragStartDetails dragDetails = null
) : base(metrics: metrics, context: context)
{
this.dragDetails = dragDetails;
}
public UserScrollNotification(
ScrollMetrics metrics = null,
BuildContext context = null,
ScrollDirection direction = ScrollDirection.idle
) : base(metrics: metrics, context: context)
{
this.direction = direction;
}
public override void dispatchScrollStartNotification(ScrollMetrics metrics, BuildContext context)
{
object lastDetails = this._controller.lastDetails;
D.assert(lastDetails is DragStartDetails);
new ScrollStartNotification(metrics: metrics, context: context, dragDetails: (DragStartDetails)lastDetails)
.dispatch(context);
}
protected ScrollNotification(
ScrollMetrics metrics = null,
BuildContext context = null
)
{
this.metrics = metrics;
this.context = context;
}
public virtual float applyPhysicsToUserOffset(ScrollMetrics position, float offset)
{
if (parent == null)
{
return(offset);
}
return(parent.applyPhysicsToUserOffset(position, offset));
}
public virtual Simulation createBallisticSimulation(ScrollMetrics position, double velocity)
{
if (this.parent == null)
{
return(null);
}
return(this.parent.createBallisticSimulation(position, velocity));
}
public virtual double applyBoundaryConditions(ScrollMetrics position, double value)
{
if (this.parent == null)
{
return(0.0);
}
return(this.parent.applyBoundaryConditions(position, value));
}
public virtual bool shouldAcceptUserOffset(ScrollMetrics position)
{
if (this.parent == null)
{
return(position.pixels != 0.0 || position.minScrollExtent != position.maxScrollExtent);
}
return(this.parent.shouldAcceptUserOffset(position));
}
public virtual double applyPhysicsToUserOffset(ScrollMetrics position, double offset)
{
if (this.parent == null)
{
return(offset);
}
return(this.parent.applyPhysicsToUserOffset(position, offset));
}
public virtual float applyBoundaryConditions(ScrollMetrics position, float value)
{
if (this.parent == null)
{
return(0.0f);
}
return(this.parent.applyBoundaryConditions(position, value));
}
public ScrollIncrementDetails(
ScrollIncrementType type,
ScrollMetrics metrics
)
{
D.assert(metrics != null);
this.type = type;
this.metrics = metrics;
}
float _getPage(ScrollMetrics position)
{
if (position is _PagePosition)
{
return(((_PagePosition)position).page);
}
return(position.pixels / position.viewportDimension);
}
float _getPixels(ScrollMetrics position, float page)
{
if (position is _PagePosition)
{
return(((_PagePosition)position).getPixelsFromPage(page));
}
return(page * position.viewportDimension);
}
public override void dispatchOverscrollNotification(ScrollMetrics metrics, BuildContext context,
double overscroll)
{
object lastDetails = this._controller.lastDetails;
D.assert(lastDetails is DragUpdateDetails);
new OverscrollNotification(metrics: metrics, context: context, overscroll: overscroll,
dragDetails: (DragUpdateDetails)lastDetails).dispatch(context);
}
public override void dispatchScrollUpdateNotification(ScrollMetrics metrics, BuildContext context,
double scrollDelta)
{
object lastDetails = this._controller.lastDetails;
D.assert(lastDetails is DragUpdateDetails);
new ScrollUpdateNotification(metrics: metrics, context: context, scrollDelta: scrollDelta,
dragDetails: (DragUpdateDetails)lastDetails).dispatch(context);
}
public ScrollUpdateNotification(
ScrollMetrics metrics = null,
BuildContext context = null,
DragUpdateDetails dragDetails = null,
float scrollDelta = 0
) : base(metrics: metrics, context: context)
{
this.dragDetails = dragDetails;
this.scrollDelta = scrollDelta;
}
float _getScrollToTrack(ScrollMetrics metrics, float thumbExtent)
{
float scrollableExtent = metrics.maxScrollExtent - metrics.minScrollExtent;
float fractionPast = (scrollableExtent > 0)
? ((metrics.pixels - metrics.minScrollExtent) / scrollableExtent).clamp(0.0f, 1.0f)
: 0;
return((_isReversed ? 1 - fractionPast : fractionPast) * (_trackExtent - thumbExtent));
}
public override void dispatchScrollEndNotification(ScrollMetrics metrics, BuildContext context)
{
object lastDetails = this._controller.lastDetails;
new ScrollEndNotification(
metrics: metrics,
context: context,
dragDetails: lastDetails as DragEndDetails
).dispatch(context);
}
public ScrollEndNotification(
ScrollMetrics metrics = null,
BuildContext context = null,
DragEndDetails dragDetails = null,
float overscroll = 0,
float velocity = 0
) : base(metrics: metrics, context: context)
{
this.dragDetails = dragDetails;
}
public bool recommendDeferredLoading(float velocity, ScrollMetrics metrics, BuildContext context)
{
D.assert(metrics != null);
D.assert(context != null);
if (parent == null)
{
float maxPhysicalPixels = WidgetsBinding.instance.window.physicalSize.longestSide;
return(velocity.abs() > maxPhysicalPixels);
}
return(parent.recommendDeferredLoading(velocity, metrics, context));
}
public OverscrollNotification(
ScrollMetrics metrics = null,
BuildContext context = null,
DragUpdateDetails dragDetails = null,
float overscroll = 0,
float velocity = 0
) : base(metrics: metrics, context: context)
{
this.dragDetails = dragDetails;
this.overscroll = overscroll;
this.velocity = velocity;
}
float _getTargetPixels(ScrollMetrics position, Tolerance tolerance, float velocity)
{
float page = _getPage(position);
if (velocity < -tolerance.velocity)
{
page -= 0.5f;
}
else if (velocity > tolerance.velocity)
{
page += 0.5f;
}
return(_getPixels(position, page.round()));
}
public override Simulation createBallisticSimulation(ScrollMetrics position, double velocity)
{
Tolerance tolerance = this.tolerance;
if (position.outOfRange())
{
double?end = null;
if (position.pixels > position.maxScrollExtent)
{
end = position.maxScrollExtent;
}
if (position.pixels < position.minScrollExtent)
{
end = position.minScrollExtent;
}
D.assert(end != null);
return(new ScrollSpringSimulation(
this.spring,
position.pixels,
position.maxScrollExtent,
Math.Min(0.0, velocity),
tolerance: tolerance
));
}
if (velocity.abs() < tolerance.velocity)
{
return(null);
}
if (velocity > 0.0 && position.pixels >= position.maxScrollExtent)
{
return(null);
}
if (velocity < 0.0 && position.pixels <= position.minScrollExtent)
{
return(null);
}
return(new ClampingScrollSimulation(
position: position.pixels,
velocity: velocity,
tolerance: tolerance
));
}
public override Simulation createBallisticSimulation(ScrollMetrics position, float velocity)
{
if ((velocity <= 0.0 && position.pixels <= position.minScrollExtent) ||
(velocity >= 0.0 && position.pixels >= position.maxScrollExtent))
{
return(base.createBallisticSimulation(position, velocity));
}
Tolerance tolerance = this.tolerance;
float target = _getTargetPixels((ScrollPosition)position, tolerance, velocity);
if (target != position.pixels)
{
return(new ScrollSpringSimulation(spring, position.pixels, target, velocity, tolerance: tolerance));
}
return(null);
}
